The invention relates to an electro-hydraulic unit for regulating the brake pressure of a hydraulic vehicle braking system. The term regulation here is understood to also include a control.
Units of this kind are used for antilock brake systems (ABS), traction control systems (TCS), electronic stability programs (ESP), and the like. EP 0 921 048 A2 has disclosed a unit of this kind. The known unit has a hydraulic block, which accommodates a hydraulic pump along with other hydraulic components such as solenoid valves. The hydraulic pump of the known unit is embodied as a two-piston pump, in which each piston is used to supply brake fluid in one of two independent brake circuits. An electric motor for driving the hydraulic pump is attached to one side of the hydraulic block. An electronic control unit for controlling electric motor and the solenoid valves is attached to the opposite side of the hydraulic block. In order to allow an electrically conductive connection (contacting) of electrical connections of the electric motor to the electronic control unit, the hydraulic block is provided with a through hole, which extends from the side of the hydraulic block to which the electronic control unit is attached to the side to which the electric motor is attached. An electrical contact, which is contained in a rod-shaped, preferably tubular insulator, is slid through the through hole in the hydraulic block; the electric motor is connected in an electrically conductive manner to the electronic control unit by means of the electrical contact.
In the electro-hydraulic unit in accordance with the-present invention, the insulator and the electrical contact contained in it are embodied so that they can move in the lateral direction. The lateral mobility is preferably achieved through an elasticity of the insulator arid of the electrical contact. Through the lateral mobility of the insulator and electrical contact, the unit according to the invention compensates for positional inaccuracies of the insulator with the electrical contact contained in it, which are the result, for example, of manufacturing and/or assembly inaccuracies, in relation to the hydraulic block. In addition, the insulator is embodied as expandable and according to the invention, it is expanded by the electrical contact contained in it so that the insulator rests without play in the through hole of the hydraulic block. In this manner, the invention achieves a precise position of the electrical contact in the hydraulic block. The invention prevents a large positional inaccuracy of the electrical contact in relation to the hydraulic block, which can otherwise occur as a result of the combined effect of a number of manufacturing and assembly inaccuracies. The electric motor is electrically connected to the electronic control unit simply by means of a plug connection with the electrical contact; the precise positioning of the electrical contact on the hydraulic block makes the electro-hydraulic unit well suited to an automated assembly. In comparison to the known unit, no additional parts are required so that no additional manufacturing costs are incurred. Another advantage of the invention is that the electrical contact in hydraulic block does not have to be sealed since the electric motor and the electronic control unit are attached to the hydraulic block in a sealed fashion and the electrical contact takes place within areas that are encompassed by the seals of the electric motor and electronic control unit. The plug connection for the electrical connection of the electric motor to the electronic control unit permits the control unit and the electric motor to be easily replaced.
In the preferred embodiment the insulator tapers toward a free end when it is not expanded, i.e. when it does not contain the electrical contact. With a round cross section, the insulator tapers conically, with a quadrilateral cross section, it tapers in the form of a pyramid or wedge. This embodiment of the invention has the advantage that when it is manufactured as an injection molded part made of plastic, the insulator can easily be removed from an injection molding tool without the injection molding tool having to be divided in the vicinity of the insulator. The electrical contact contained in the insulator expands the insulator, preferably only in the vicinity of its free end, in the opposite direction so that at the point of its greatest expansion, the insulator has at least the same dimension across as its largest point when it is not expanded. Through this expansion, it is possible to secure the insulator without play in a through hole of a constant diameter in the hydraulic block, in the vicinity of a free end of the insulator. Over its remaining length, the insulator has play in the through hole in the hydraulic block so that it can move laterally, along with the electrical contact contained in it.
In another embodiment, the insertion depth to which the electrical contact is inserted into a mating contact is not limited. This embodiment of the invention achieves a compensation in the longitudinal direction of the electrical contact between the electrical contact and a mating contact, which compensates for hydraulic blocks of different thickness and electronic control units of different heights.